Duct cover for directing a fluid therethrough

Abstract

A duct cover for use with a duct within a vehicle, the duct cover operative for directing a fluid flow. The duct cover being further operative for minimizing the entrance of foreign object debris into the duct. The duct cover has a flow directing honeycomb portion for conducting the passing fluid flow in a preferred direction. The flow directing honeycomb comprises an array of continuous, polygon shaped open cells which are biased with respect to the initial fluid flow direction. The periphery of the flow directing honeycomb is rigidized to stiffen the same for minimizing the displacements thereof. The rigidity is provided by a framing member comprising upper and lower skin structures affixed to a core material. The framing member is preferably adhesively bonded to the flow directing honeycomb by means of a foaming adhesive and a barrier member. The barrier member is operative for minimizing the expansion of the foaming adhesive into the open cells of the honeycomb. In order to improve the low observability characteristics of the structure, the cells of the flow directing honeycomb are preferably coated with a radar absorbent material, such as carbon, which acts to minimize the amount of electromagnetic energy that is reflected therefrom.

What is claimed is: 
     
       1. A duct cover operative for directing a fluid flow, the duct cover for use in combination with a duct within a vehicle, the fluid flow having an initial direction and a final direction, wherein the duct cover comprises: a flow directing honeycomb, said honeycomb comprising an array of cells defined by an associated plurality of cell walls, said cells for conducting a fluid flow therethrough, said cells having a length sufficient for effecting a change in the fluid flow direction, and wherein said cells are biased with respect to the initial direction of the fluid flow for channeling the fluid flow from the initial direction to the final direction; and   a triangular framing member for rigidizing the flow directing honeycomb, the triangular framing member including skin structures which define at least two sides of said triangular framing member, and a core material disposed between and affixed to said skin structures, wherein one side of said triangular framing member forms a peripheral side of said flow directing honeycomb.   
     
     
       2. The duct cover according to claim 1 wherein said bias of said cells is in a range between about 20 degrees and about 70 degrees. 
     
     
       3. The duct cover according to claim 2 wherein said bias of said cells is about 45 degrees. 
     
     
       4. The duct cover according to claim 1 wherein said core material of said triangular framing member is honeycomb, said honeycomb comprising an array of cells, and wherein said skin structures are made from a least one ply of fiber reinforced resin matrix composite material. 
     
     
       5. The duct cover according to claim 4 wherein said honeycomb core material of said triangular framing member is an integral extension of said flow directing honeycomb. 
     
     
       6. The duct cover according to claim 5 wherein said honeycomb core material of said triangular framing member has a plurality of cells filled with a stiffening material so as to further stiffen said core material. 
     
     
       7. The duct cover according to claim 6 wherein said stiffening material extends between said at least two skin structures so as to form a third side of the triangular framing member and wherein said stiffening material includes an epoxy resin material. 
     
     
       8. The duct cover according to claim 4 wherein said honeycomb core material of said triangular framing member is adhesively bonded to said flow directing honeycomb. 
     
     
       9. The duct cover according to claim 8 wherein said adhesive bond comprises a foaming adhesive layer and a barrier member, said barrier member for minimizing the expansion of said foaming adhesive layer. 
     
     
       10. The duct cover according to claim 9 wherein said barrier member is disposed between said foaming adhesive layer and said flow directing honeycomb for reducing the expansion of said foaming adhesive layer into said flow directing honeycomb cells. 
     
     
       11. The duct cover according to claim 9 wherein said barrier member is disposed between said foaming adhesive layer and said honeycomb core material for reducing the expansion of said foaming adhesive layer into said cells of said honeycomb core material. 
     
     
       12. The duct cover according to claim 9 wherein said barrier member comprises a layer of film adhesive. 
     
     
       13. The duct cover according to claim 9 wherein said barrier member comprises at least one ply of fiber reinforced resin matrix composite material and a layer of film adhesive, said film adhesive layer being disposed on said composite material. 
     
     
       14. The duct cover according to claim 4 wherein said flow directing honeycomb is made from fiberglass material and said honeycomb core material is made from a phenolic resin material. 
     
     
       15. The duct cover according to claim 1 wherein said flow directing honeycomb is made from fiberglass material. 
     
     
       16. A duct cover operative for directing a fluid flow while minimizing the reflection of electromagnetic energy, the duct cover for use in combination with a duct within a vehicle, the fluid flow having an initial direction and a final direction, wherein the duct cover comprises: a flow directing honeycomb, said honeycomb comprising an array of cells defined by an associated plurality of cell walls, said cells for conducting a fluid therethrough, said cells having a length sufficient for effecting a change in the fluid flow direction and being biased with respect to the initial direction of the fluid flow for channeling the fluid flow from the initial direction to the final direction, said honeycomb further including a radar absorbent material; and   a triangular framing member for rigidizing the flow directing honeycomb, the triangular framing member including skin structures which define at least two sides of said triangular framing member, and a core material disposed between and affixed to said skin structures, wherein one side of said triangular framing member forms a peripheral side of said flow directing honeycomb.   
     
     
       17. The duct cover according to claim 16 wherein said radar absorbent material is disposed on said cell walls of said flow directing honeycomb. 
     
     
       18. The duct cover according to claim 17 wherein the thickness of said radar absorbent material varies along said cell length. 
     
     
       19. The duct cover according to claim 17 wherein the constituent electrical properties of said radar absorbent material vary along said cell length. 
     
     
       20. The duct cover according to claim 17 wherein said radar absorbent material is carbon. 
     
     
       21. The duct cover according to claim 16 wherein said bias of said cells is in a range between about 20 degrees and about 70 degrees. 
     
     
       22. The duct cover according to claim 21 wherein said bias of said cells is about 45 degrees. 
     
     
       23. The duct cover according to claim 16 wherein said core material of said triangular framing member is honeycomb, said honeycomb comprising an array of cells, and wherein said skin structures are made from at least one ply of fiber reinforced resin matrix composite material. 
     
     
       24. The duct cover according to claim 23 wherein said honeycomb core material of said triangular framing member is an integral extension of said flow directing honeycomb. 
     
     
       25. The duct cover according to claim 24 wherein said honeycomb core material of said triangular framing member has a plurality of cells filled with a stiffening material so as to further stiffen said core material. 
     
     
       26. The duct cover according to claim 25 wherein said stiffening material extends between said at least two skin structures so as to form a third side of the triangular framing member and wherein said stiffening material includes an epoxy resin material. 
     
     
       27. The duct cover according to claim 23 wherein said honeycomb core material of said triangular framing member is adhesively bonded to said flow directing honeycomb. 
     
     
       28. The duct cover according to claim 27 wherein said adhesive bond comprises a foaming adhesive layer and a barrier member, said barrier member for minimizing the expansion of said foaming adhesive layer. 
     
     
       29. The duct cover according to claim 28 wherein said barrier member is disposed between said foaming adhesive layer and said flow directing honeycomb for reducing the expansion of said foaming adhesive layer into said flow directing honeycomb cells. 
     
     
       30. The duct cover according to claim 28 wherein said barrier member is disposed between said foaming adhesive layer and said honeycomb core material for reducing the expansion of said foaming adhesive layer into said cells of said honeycomb core material. 
     
     
       31. The duct cover according to claim 28 wherein said barrier member comprises a layer of film adhesive. 
     
     
       32. The duct cover according to claim 28 wherein said barrier member comprises at least one ply of fiber reinforced resin matrix composite material and a layer of film adhesive, said film adhesive layer being disposed on said composite material. 
     
     
       33. The duct cover according to claim 32 wherein said fibers of said composite material are made from an aromatic polyamide material. 
     
     
       34. The duct cover according to claim 23 wherein said flow directing honeycomb is made from fiberglass material and said honeycomb core material is made from a phenolic resin material. 
     
     
       35. The duct cover according to claim 23 wherein said fibers of said skin structures are made from an aromatic polyamide material. 
     
     
       36. The duct cover according to claim 16 wherein said flow directing honeycomb is made from fiberglass material.